Development of a method to estimate organ doses for pediatric CT examinations

Journal Article · Sun May 15 04:00:00 EDT 2016 · Medical Physics

DOI:https://doi.org/10.1118/1.4944867· OSTI ID:22620872

Perisinakis, Kostas; Damilakis, John ^[1]

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1. Department of Medical Physics, University Hospital of Heraklion, Faculty of Medicine, University of Crete, P.O. Box 1352, Iraklion, Crete 71110 (Greece)

Purpose: To develop a method for estimating doses to primarily exposed organs in pediatric CT by taking into account patient size and automatic tube current modulation (ATCM). Methods: A Monte Carlo CT dosimetry software package, which creates patient-specific voxelized phantoms, accurately simulates CT exposures, and generates dose images depicting the energy imparted on the exposed volume, was used. Routine head, thorax, and abdomen/pelvis CT examinations in 92 pediatric patients, ranging from 1-month to 14-yr-old (49 boys and 43 girls), were simulated on a 64-slice CT scanner. Two sets of simulations were performed in each patient using (i) a fixed tube current (FTC) value over the entire examination length and (ii) the ATCM profile extracted from the DICOM header of the reconstructed images. Normalized to CTDI{sub vol} organ dose was derived for all primary irradiated radiosensitive organs. Normalized dose data were correlated to patient’s water equivalent diameter using log-transformed linear regression analysis. Results: The maximum percent difference in normalized organ dose between FTC and ATCM acquisitions was 10% for eyes in head, 26% for thymus in thorax, and 76% for kidneys in abdomen/pelvis. In most of the organs, the correlation between dose and water equivalent diameter was significantly improved in ATCM compared to FTC acquisitions (P < 0.001). Conclusions: The proposed method employs size specific CTDI{sub vol}-normalized organ dose coefficients for ATCM-activated and FTC acquisitions in pediatric CT. These coefficients are substantially different between ATCM and FTC modes of operation and enable a more accurate assessment of patient-specific organ dose in the clinical setting.

• OSTI ID: 22620872
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 5 Vol. 43; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
ABDOMEN
CHEST
COMPUTER CODES
COMPUTERIZED TOMOGRAPHY
DOSIMETRY
EYES
IMAGES
KIDNEYS
MONTE CARLO METHOD
PATIENTS
PEDIATRICS
PELVIS
PHANTOMS
RADIATION DOSES
REGRESSION ANALYSIS
SIMULATION
THYMUS